Bulletin d’avalanche

Continental

Valdez Avalanche Center
Voir sur la carte

Danger d’avalanche

Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
Open full map
Périmé — ce bulletin a expiré last year. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

The avalanche hazard is Moderate at all elevations.  Human triggered avalanches are possible in terrain steeper than 35°, up to 1+ foot in depth.  Wet loose avalanches are the main concern below 4000 feet.  Above 4000 feet dense storm slabs can be expected that may be sensitive to human triggers in specific areas.  

This is the last avalanche forecast of the season.  Thanks to everyone who used and contributed to the Valdez Avalanche Center this season!  

Problèmes avalancheux

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    The stormy wet April continues with temperatures remaining above freezing below 2000' since the last clear day on 4/25 brought a solid overnight freeze.  Above 2000', the temperatures have dipped below the freezing mark, but only by a few degrees during the nighttime hours.  This has caused the snowpack to become isothermal below 2000', travel in steep terrain is not recommended at low elevations, however, most steep terrain has either already avalanched or is free from snow.

    Above freezing temperatures during the day above 2000' are creeping deeper into the snowpack as well as up in elevation.  Despite these warm temps, wet loose activity is expected to be confined to low elevations and solar aspects below 4000' during the day today due to thick cloud cover and accumulating snow above 4000'.

    Pay attention to how much wet snow is at the surface in combination with the terrain you are traveling on.  In areas where more than 6 inches of wet snow exists on slopes 35° and steeper, wet loose avalanches will be possible, both human triggered and natural.  The potential of wet loose activity directly correlates to the vertical relief of a slope combined with how wet the snow is at the surface.

    Plan your route to avoid slopes steeper than 35° with more than 6 inches of wet snow (can form a snowball that you can squeeze water out of). This includes the terrain you are travelling on as well as slopes above you.

    4/19- Active wet loose activity on the North Buttress of Mt Francis during sunny weather directly after heavy snowfall

    Photo: Gareth Brown

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    Strong southerly flow off the Gulf of Alaska is bringing strong Southeast winds along with wet heavy snow above 3000' and rain at low elevations. Winds and precipitation are expected to have peaked last night, although, both are forecasted to continue today.  Depending upon proximity to the coast, .75"-1.5" of storm total water is expected; this will translate to 4-10" of dense snow accumulations above 4000'.  Nicks weather station at 4200' has already picked up 6" of new snow as of 5:30 AM.

     Strong southeast winds with gusts in the 30's will build deeper pockets of storm snow up to 1+ feet in depth on the lee side of high elevation ridgelines.  These pockets of wind loaded snow are not expected to be widespread, or deep due to the dense snow that will be resistant to redistribution.  Where these pockets of wind loaded snow exist in terrain steeper than 35° human triggered avalanches will be possible.  Pay attention to new snow fall amounts and how well the new snow is bonding with older surfaces.  Test slopes and hand shear pits are good tools for today's assessment of this problem.  It will also be important to watch for the effect that wind has had on the new snow.  How much wind redistribution has occurred?  What slopes might be loaded?

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    2–3

    Overcast skies over the last week have limited upper elevation observation of the 4/4 persistent weak layer and its development to just a few locations.  The observations that have been obtained along with the general trend of the weather has been pointing to the possibility of triggering an avalanche at this layer to be continuing to decrease and is now unlikely within our core forecast area.  Warm temperatures have been promoting bonding and strengthening of the 4/4 interface.  We are now receiving a small load of snow above 4000' over the last 24 hours however this has been the first load since the last major shot of snow on the 17th.  This has allowed the April persistent slab to settle and bond.

    The most recent snowfall is not expected to increase the sensitivity of the 4/4 persistent weak layer in our forecast area.  Human triggered persistent slab avalanches 2-3+ feet in depth are unlikely but not impossible in isolated areas of steep and complicated terrain within our core forecast zone.  The development of this weak layer's sensitivity is unknown in high glaciated valleys outside of our core forecast area due to no recent observations from these areas.  

    Slope by slope assessment is advised when travelling in steep terrain.  Keep in mind that slab sensitivity can increase during the heat of the day as the upper snowpack heats up.

    (4/15/2025)

    Hiker triggered avalanche on Local Spines . Crown depth 3-4 feet/ 500-600 feet wide/ multiple step downs.

    SS-AFu-R3-D3

Avalanche Discussion

Observed Avalanche Activity last 72 hours: 

NONE

Forecast Discussion:

The cloudy and wet April weather continues today with rain below 3000' and moderate snow above.  The snow line dropped to 1000' at the coast overnight, but is expected to climb to 3000' during the day.  Wet loose avalanches are the main concern and should be treated seriously on slopes steeper than 35° that are becoming active or have wet snow.  Cornices, icefalls, and snow bridges will all be affected by above freezing temperatures today and may become unstable.  

Moderate snowfall is expected to continue today with an additional 2-4" above 4000', adding to the 6" that was recorded at Nicks this morning.  Shallow stom slabs that have accumulated over the last 24 hours up to 10" deep can be expected above 5000' with wind loaded pockets 1+ feet in depth being the most likely areas to encounter instabilities.  This avalanche problem is only expected to exist in the Maritime and Intermountain forecast zones.  The Continental zone is not expected to have received sufficient snow to create an instability concern.

Below 4000' pay attention to how wet the snow surface is combined with the terrain's potential for wet loose avalanches. This includes the terrain that you are on as well as what is above you.  Above 4000' pay attention to new snowfall amounts, how well that new snow is bonding and to what degree the recent storm wind has redistributed the new snow.

 

Additional Information:

Avoid Cornices. This is the time of year when cornices begin to fail naturally.  Cornice fall will have the potential to create large destructive avalanches.

A weather and snowpack season history is available by clicking on the Season Summary tab, which is located below the bottom line statement once you have entered the full forecast.

Season Snowfall Data

Location 24 hour Snowfall Inches- 4/30 24 hour Snow Water Equivalent Inches Height of Snow April Snowfall Inches Season Total Snowfall Valdez    0    N/O    22      2     N/O     Thompson Pass   N/O    N/O   N/O     N/O    ~500 Nicks    6    N/O    155    N/O N/O 46 Mile    0     0   6    10 N/O

Régions couvertes